ue5-build-verify

name	ue5-build-verify
description	Post-code-write verification gate for Unreal Engine 5 C++ projects. Scans all modified files for known silent-failure patterns specific to this codebase (wrong SLOG macro syntax, FString::FromBool, EditAnywhere, etc.) then triggers a full UE5 build and surfaces every error/warning with file+line. Run automatically after writing any .cpp/.h file in the project.
user-invocable	true
allowed-tools	["Bash","Grep","Glob","Read","Edit"]

UE5 Build Verify

Catches codebase-specific anti-patterns and build errors immediately after code is written — before they accumulate across multiple files and sessions.

Root Cause This Skill Was Created From

Phase 4 (April 20, 2026): An agent added SLOG_EVENT instrumentation using a brace-initializer syntax {{"key", val}} that is invalid for these variadic macros. It also used FString::FromBool() which does not exist in UE5. Neither error was caught because no build was run before committing. The result was 150+ cascade errors across 10 files that had to be manually traced and fixed in a later session.

Rule: Every time C++ code is written into this project, this skill runs.

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When to Activate

• Automatically after writing or editing any .cpp or .h file in the project
• Manually via /ue5-build-verify when you want an explicit gate before committing
• Always when adding new macro usage (SLOG_, UPROPERTY, UFUNCTION, DECLARE_)

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Step 1: Static Pattern Scan (fast, runs first)

Grep all staged/modified .cpp and .h files for known bad patterns before invoking the compiler. Fix any hits immediately, then proceed to Step 2.

Pattern Checklist

Run these grep checks against every modified file:

1. Wrong SLOG macro syntax (brace-initializer)

# BAD: {{"key", value}} — compiles to nothing, causes cascade parse errors
grep -n '{\s*{' <file> | grep -v "//.*{{"

Correct form: Metadata.Add(TEXT("key"), value); as semicolon-separated statements inside the macro's variadic arg.

2. FString::FromBool — does not exist in UE5

grep -n "FString::FromBool" <file>

Fix: replace with x ? TEXT("true") : TEXT("false")

3. EditAnywhere — forbidden by project standards

grep -n "EditAnywhere" <file>

Fix: replace with EditDefaultsOnly or EditInstanceOnly

4. Hardcoded FName string literals in BT nodes

grep -n 'GetValueAs.*TEXT("' <file>
grep -n 'SetValueAs.*TEXT("' <file>

Fix: use the FName key name properties from the controller/node header.

5. FBlackboardKeySelector missing AddFilter in constructor

grep -n "FBlackboardKeySelector" <file>

For every FBlackboardKeySelector property: verify constructor has AddObjectFilter/AddBoolFilter/AddVectorFilter AND InitializeFromAsset override has ResolveSelectedKey. Both required — silent failure without both.

6. GameplayStatics cross-system calls (forbidden)

grep -n "UGameplayStatics::" <file>

Fix: use TActorIterator, cached TWeakObjectPtr, or Observer delegates.

7. ConstructorHelpers (forbidden)

grep -n "ConstructorHelpers::" <file>

Fix: use EditDefaultsOnly UPROPERTY and assign in Blueprint.

8. Polling in Tick / BTService TickNode

grep -n "GetAuthGameMode\|GetGameMode" <file>

If inside a Tick/TickNode/TickTask function: forbidden. Use delegate binding.

9. Missing semicolon after SLOG macro call

grep -n "^    SLOG_" <file> | grep -v ",$\|;$\|)$"

SLOG macros expand to { ... } blocks — they don't need a trailing semicolon, but the Metadata.Add lines inside the variadic body each need one.

10. /** */ docblock comments (style violation)

grep -n "/\*\*" <file>

Fix: replace with // line comments per Nick Penney AAA standards.

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Step 2: UE5 Compiler Build

After the static scan passes (zero hits), run the full build:

"C:\Program Files\Epic Games\UE_5.4\Engine\Build\BatchFiles\Build.bat" \
  END2507Editor Win64 Development \
  -Project="C:\Users\daley\UnrealProjects\BaseGame\WizardJam2.0.uproject" \
  -WaitMutex -FromMsBuild -architecture=x64

Interpreting Build Output

Parse the output for these patterns:

Pattern	Meaning	Action
error C2065: 'Metadata': undeclared identifier	SLOG called outside enabled block or wrong syntax	Check macro call in that file
error C2059: syntax error: '{'	Brace-initializer in SLOG variadic arg	Convert to Metadata.Add() statements
error C3861: 'FromBool': identifier not found	FString::FromBool() usage	Replace with ternary
error C2614: illegal member initialization	Property in constructor init list but not declared	Check header declaration order
warning C5038: ... will be initialized after	Init list order doesn't match declaration order	Reorder init list to match header
'->': trailing return type not allowed	Cascade from earlier syntax error	Fix the root error first
missing function header (old-style formal list?)	Cascade from earlier syntax error	Fix the root error first

Cascade error rule: When you see 50+ errors, look for the FIRST error in the output — it is almost always the root cause. Fix it and rebuild before touching anything else.

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Step 3: Resolve and Re-Verify

For each error found:

1. Open the file at the reported line number
2. Apply the fix from the pattern checklist or error table above
3. Re-run Step 1 static scan on the changed file
4. Re-run Step 2 build — do not stop until exit code is 0

Do not commit until the build exits with code 0.

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SLOG Macro Reference (this codebase)

The SLOG_* macros in Plugins/StructuredLogging/Source/StructuredLogging/Public/StructuredLoggingMacros.h use __VA_ARGS__ to inject code into a block that already has a TMap<FString,FString> Metadata local variable declared.

// ✅ CORRECT — variadic body is semicolon-separated Metadata.Add() statements
SLOG_EVENT(this, "AI.Flight", "FlightTargetSet",
    Metadata.Add(TEXT("target_location"), TargetLocation.ToString());
    Metadata.Add(TEXT("pawn_name"), GetPawn()->GetName());
)

// ✅ CORRECT — no metadata (variadic arg omitted entirely)
SLOG_EVENT(this, "AI.Flight", "FlightTargetCleared")

// ❌ WRONG — brace-initializer. Causes cascade parse errors across entire file.
SLOG_EVENT(this, "AI.Flight", "FlightTargetSet", {
    {"target_location", TargetLocation.ToString()}
})

// ❌ WRONG — FString::FromBool does not exist in UE5
Metadata.Add(TEXT("is_flying"), FString::FromBool(bIsFlying));

// ✅ CORRECT — ternary instead
Metadata.Add(TEXT("is_flying"), bIsFlying ? TEXT("true") : TEXT("false"));

No trailing semicolon after the closing ) — the macro expands to a { } block.

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FBlackboardKeySelector Reference (this codebase)

Every FBlackboardKeySelector property requires both of these or it silently returns IsSet() == false at runtime even when configured in the editor:

// In constructor — registers valid key types for editor dropdown
MyKey.AddBoolFilter(this, GET_MEMBER_NAME_CHECKED(UMyBTNode, MyKey));
// Also: AddObjectFilter(..., AActor::StaticClass()), AddVectorFilter(...)

// In InitializeFromAsset override — resolves name to actual BB slot
void UMyBTNode::InitializeFromAsset(UBehaviorTree& Asset)
{
    Super::InitializeFromAsset(Asset);
    if (UBlackboardData* BBAsset = GetBlackboardAsset())
        MyKey.ResolveSelectedKey(*BBAsset);
}

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Quick Reference: Forbidden Patterns

Pattern	Why Forbidden	Fix
EditAnywhere	Allows instance override of defaults	EditDefaultsOnly or EditInstanceOnly
FString::FromBool(x)	Doesn't exist in UE5	x ? TEXT("true") : TEXT("false")
UGameplayStatics::GetGameMode	Tight coupling	Cache + Observer delegates
ConstructorHelpers::FObjectFinder	Loads at construction time	EditDefaultsOnly + Blueprint assign
/** */ docblocks	Style violation (Nick Penney standard)	// line comments only
Hardcoded FName strings in BT nodes	Not designer-configurable	FName property + QuidditchBBKeys:: constants
Polling in Tick() / TickNode()	Breaks Observer pattern	Delegate binding at BeginPlay

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Notes

• This skill was created after the Phase 4 build failure (April 26, 2026) where 37 bad SLOG calls across 10 files went undetected because no build was run.
• The UE5 build command takes ~2-5 minutes on this machine — run it every session, not just before commit.
• The static pattern scan (Step 1) is fast and should run after every file write.
• "Fix it now" is always cheaper than "fix it later across 10 files."